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11.
Karin Hain Christoph Hugenschmidt Philip Pikart Peter B?ni 《Science and Technology of Advanced Materials》2010,11(2)
A friction stir welded (FSW) Al alloy sample was investigated by Doppler broadening spectroscopy (DBS) of the positron annihilation line. The spatially resolved defect distribution showed that the material in the joint zone becomes completely annealed during the welding process at the shoulder of the FSW tool, whereas at the tip, annealing is prevailed by the deterioration of the material due to the tool movement. This might be responsible for the increased probability of cracking in the heat affected zone of friction stir welds. Examination of a material pairing of steel S235 and the Al alloy Silafont36 by coincident Doppler broadening spectroscopy (CDBS) indicates the formation of annealed steel clusters in the Al alloy component of the sample. The clear visibility of Fe in the CDB spectra is explained by the very efficient trapping at the interface between steel cluster and bulk. 相似文献
12.
Scientific journals claim that correspondence sections are for post-publication peer review. We compared the conditions for
submission and the bibliometrics of letters-to-editors published in leading medical journals in 2002 and 2007 using journal-derived
information and data from PubMed and Journal Citation Reports. The median time limit for letter submissions decreased from
6 to 3.5 weeks, the median word limit from 400 to 350. The median number of letters per published article was near one in
both years. Only about half of the letters were followed by an author reply in either year. Electronic response systems were
available for four journals in 2007. 相似文献
13.
Aim of the present study was to evaluate the effect of cefamandole, cefuroxime and cefoxitin on the level of gastrointestinal (GI) colonization by Candida albicans in humans. Twenty-eight adult patients received one of these three cephalosporins for 10 days, as treatment of infection, and were studied prospectively. Quantitative stool cultures for yeasts were performed immediately before, at the end, and 1 week after discontinuation of treatment. All three antibiotics caused an increase of the yeast concentration in the fecal flora. The increase caused by cefoxitin was the highest (2.5 log10 CFU/g of stool). Our results suggest that the cephalosporins tested cause minor increases of the colonization of the GI tract by C. albicans. 相似文献
14.
15.
Abdelhamid Mellouk Saïd Hoceïni Yacine Amirat 《International Journal of Communication Systems》2007,20(10):1113-1130
In this paper, we propose two adaptive routing algorithms based on reinforcement learning. In the first algorithm, we have used a neural network to approximate the reinforcement signal, allowing the learner to take into account various parameters such as local queue size, for distance estimation. Moreover, each router uses an online learning module to optimize the path in terms of average packet delivery time, by taking into account the waiting queue states of neighbouring routers. In the second algorithm, the exploration of paths is limited to N‐best non‐loop paths in terms of hops number (number of routers in a path), leading to a substantial reduction of convergence time. The performances of the proposed algorithms are evaluated experimentally with OPNET simulator for different levels of traffic's load and compared with standard shortest‐path and Q‐routing algorithms. Our approach proves superior to classical algorithms and is able to route efficiently even when the network load varies in an irregular manner. We also tested our approach on a large network topology to proof its scalability and adaptability. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
16.
选用含有亲水性羧基、酸酐基、磺酸基、聚环氧乙烷侧链的单体共聚合成了3种羧酸型减水剂,针对4种不同产地的P.O 42.5水泥,测定了在较低水灰比(mw/mc=0.29)下水泥净浆流动度及30 min经时变化,混凝土坍落度及180 min经时变化.净浆流动度30 min损失小于13.8%,混凝土坍落度60 min损失小于15%.3种羧酸型减水剂与不同水泥均具有良好的相容性. 相似文献
17.
Ji?í Jeništa Hidemasa Takana Hideya Nishiyama Milada Bartlová Vladimír Aubrecht Petr K?enek Viktor Sember Alan Mašláni 《Computer Physics Communications》2011,182(9):1776-1783
The paper presents numerical simulations of the discharge and the near-outlet regions of the hybrid-stabilized argon–water electric arc. Two different numerical methods for solving the set of conservative equations for the continuity, momentum and energy have been applied. The major difference between the results using the two methods occurs in the temperature distribution in arc fringes within the discharge chamber. This fact influences the potential drop, overpressure, reabsorption of radiation and arc efficiency. It is shown that the radial profiles of temperature at the exit nozzle are less influenced by different temperature distribution within the discharge chamber. Comparison with chosen experimental temperature profiles shows very good agreement. 相似文献
18.
Frank Diatze Karsten Gloe Renate Jacobi Peter Mūni Jörg Beger Michael Petrich 《溶剂提取与离子交换》2013,31(2):223-247
The complex forming and extraction properties of various open-chain and two cyclic oxathia alkanes towards silver have been studied. The investigations confirm the direct proportionality between extraction constants and related complex stability constants.The extraction of silver by open-chain oxethie alkenee is greeter than by structurally analogoue thicacrown compounds. This fact and the determined stability constants show an absence of a macrocyclic effect during complex formation. The differences of extraction power between the various open-chain compounds can be interpreted on the basic o f the coordinative saturation and stereochemiatry of the silver ion, on the size o f the poesible chelate rings, and on the complexing capability o f the ether oxygen atoms. 相似文献
19.
A numerical procedure was employed to evaluate hydrated water attached to the extractable nitric acid/iso-butanol complex. The hydratation number was found to be 11, a value favourable in comparison to the hydratation numbers published for straight chain alcohols extractants. Of several tested approaches, the fourth order interaction Scatchard equation offers water activity coefficients in the alcohol phase which are in close agreement with the measured ones. 相似文献
20.